You said when you click on sync all users, nothing changed on MailChimp.
These are the data I am seeing:
http://prntscr.com/op2i0b
You can see there are data, that means sync is working. If you want to check live please make an activity then check.
I created a new course
test course and purchased that course so according to settings, If we click on sync all users (
Enable Subscribe option in WooCommerce Checkout) It should be added in MailChimp List(
Woocomerce opcion de suscripción).
I clicked and you can see new entries in
Woocomerce opcion de suscripción list.
Refer:
http://prntscr.com/op2h7b
Please check at your end and reply. Now it should work.
I am really thankful for your time.